Walter mills



. (No Model.) y

W. MILLS.

Y PROCESS 0F PURIFYING OILS. No. 532,682. Patented Jan. 15, 1895.

ms cams versus cn. vamuumo. WASHINGTON. n. c

' UNITED; 'STATES`r A'PATENT OFFICE.

WALTER MILLS, oE LoNDoN, ENGLAND, AssIeNoR or ONE-HALE To HOWARD ovIATig on NEW YORK, N. Y.

PROCESS OF PURl-FYING O'ILVS.

SPECIFICATION forming part of Letters Patent No. 532,682, dated January 15, 1895.

Application led December 11, 1891. Renewed April 21, 1894. Serial No. 508,528.. (No model.) Ifatented in England October 23,

To all whom it may concern: .v c Be it known thatI, WALTER MILLS, a subject of the Queen of Great Britain, residing at London, England, have invented certain new and useful Improvements in' Purifying Oils and Fats,

. 1891;) and I do hereby declare that the following is a full, clear, and exact description of' the invention, which will enable others skilled in the art to which it appertains to make and use the same. c v

My invention relates to a process for purifying oils and fats and is based upon a discovery which I have made, namely, that if sulphuric tri-oxide, at a suitable temperature,

say 120 to 130 Fahrenheit, be brought into brought in contact with, but the general ruleis that trioxides are decomposed by contact with organic substances, and actual operation has proved it to be the case in my process. The impurities before referred to vary according to the constituents of the oil or fat, but they may be generally described as substances containing the radical CnHZ-n-H in a more or less advanced state of oxidation, and in some cases hydric sulphide (H2S) is present.' These impuritiesare also of, a verycomplex and intricate character, but I nd that the sulphuricjtrioxide eectually destroys or reduces them. 7 This action is so energetic that in most cases it is necessary to dilute the sulphuric tri-oxide with a neutrall gas before using it. Y

In the accompanying drawings I have shown an apparatus for carrying out my process.

(for which I have obtained British Patent N o. 18,224, dated October 23,'

Referring, however, to said drawings, ar, is the vessel which I call the mixer in which the fats or oils to be treated are placed.

b is the retort in which sulphuric trioxide is introduced and heated until it assumes a gaseous form or gives off gaseous sulphuric trioxide. V

c is a receptacle for the gaseous sulphuric trioxide producedvin the retort, b. j

d is the apparatus in which the atmospheric .air is dried and e is a pump in which said air is heated by compression.

f is a vessel in which the gas and hot dry air are forced by the pumps g and e respectively, and in which they become united previously to their introduction into themixer ct.

The mixer a.' is a cylindrical vessel constructed'of iron, capable of supporting a pressureof about sixtypounds to the square inch.

Ahollow shaft h, so arranged as to revolve leating with the hollow shaft h as shown in Hthe drawings.

4 The obj ect of placing the vessel f in a tank is to enable the mixed gas and air to be kept at any desired temperature by `lling the tank with steam, water or other iiuid.

The retort b is heated by means of a stove or steam coil so as to heat the solid sulphuric trioxide placed therein to above a temperature of 120 Fahrenheit at which temperature gaseous sulphuric trioxide is produced which passes out'through a pipe Z into the receptacle or holder c which is packed or lagged on the outside with suitable non-conducting material m. From the gas holder c the trioxide gas is' drawn by the pump g vas required, through the suction pipe n and delivered by said pump, through the delivery pipe o and through a pipe p into the vessel f.

The apparatus d for drying the atmospheric air is constructed with a number of shelves or trays q on which is placed asubstance such as chloride of calcium,which will readily absorb moisture. The trays q are provided with holes iitted with nozzles r so as to allow free circulation of the atmospheric air through or over the substance placed upon the trays q. The vessel d is entirely closed except at its base which is of conical shape and is inserted in a conical shaped vessel or receptacle s containing ice. Tubes t are so fixed between the inner side of the receptacle s and the base of vessel d that air can pass freely down them and enter the said vessel, being cooled in its passage by the ice. The air passes upward in the direction indicated by the arrows and having been freed from moisture passes through the sdction pipe lu. to the compression pump e whereby it is heated and delivered through a pipe e into the same pipep which receives the sulphuric trioxide gas and discharges them together into the vessel f in which they become intimately mixed before passing oft through the pipe la, hollow shaft 7L and perforated pipes 1I into the fat or oil in the mixer a.. The diluted sulphuric trioxide is here decomposed into its constituents, sulphurous dioxide and oxygen both of which being in a nascent state bleach, deodorize and `purify the fat or oil with which they are brought into contact.

The pumps g and e are actuated by a crank w operated by a pulley driven from any suitable motor. Suitable valves and stopcocks are provided to regulate the iiow of the gaseous sulphuric trioxide and of the atmospheric air and to draw off." the contents of the various vessels.

Some oils, such as petroleum, can be treated in a cold state while other oils and fats require to be heated or melted. I prefer, however, in all cases to heat the fat or oil to about 120 Fahrenheit. As it is best to do this while the fat or oil is in the mixer a, I provide a tank y around the base of the mixer arranged to be heated by any suitable means.

In practice I iind that it is generally ad vantageous to conduct the operation under a pressure of (but not in anycaseexceeding) two atmospheres as the action of the tri-oxide is thereby accelerated and a more perfect contact with the sulphuric tri-oxide brought about.

Sulphuric tri-oxide is at ordinary temperatures a solid and it is therefore generally in1- practicable to use it in that condition although there are cases in which it may be so used. I find that it is best in most cases to melt the fat or oil (if it requires melting) and to bring it to a temperature of about 120to 130 Fahrenheit in those cases where pressure is not used. The sulphuric tri-oxide is raised to the same temperature, at which temperature it is a gas.

In cases where the tri-oxide requires to be diluted, it may be readily mixed with dry at ,f

mospheric air raised to about the same temperature as the gas. In this condition it is readily capable of being brought into contact with the fat or oil by suitable mechanical means.

When the sulphuric tri-oxide has done its work upon the fat or oil this latter substance is largely charged with the products ofthe decomposition of thesulphuric trl-oxide and with the results of their action upon the fat or oil. These must be removed from the fat or oil in order to render it a commercial article. I effect this in most cases by filtering the fat or oil through animal charcoal which I find is the most advantageous ltering medium both on the ground oteconomy as well as because of its eliicient action. cases Where the fat or oil readily solidifies the ilter-bed which contains the animal charcoal or other filtering medium must be kept at a suitable temperature, say at about 130 Fahrenheit. There are also cases in which the `fat or oil is so highly charged with the sulphurous di-oxide, produced by the decomposition of the sulphuric tri-oxide` that it is desirable toexpose the fat or oil to the action of steam which is best used superheated to a slight degree. In these circumstances the sul- `phurous di-oxide is readily removed, after which any carbonaceous materials present in the fat or oil may be eliminated by filtration Ithrough animal charcoal. I am aware that sulphuric acid has been used in purifying oils and fats but the oper ation of sulphuric trioxide as employed by me jis essentially diierent from the action of sulphuric acid. Sulphuric acid when mixed with oils or fats forms substitution products therewith, in most cases entirely altering the nature of the oil or fat treated. Thus cocoa nut-oil so treated becomes harder and darker, lwhereas sulphuric trioxide has no such action. The trioxide can also be diluted and can also be intimately mixed with the oils and fats. The action of the trioxide consists in oxidizing the complex substance to which joils and fats owe their rancidity and thus alcohols and incipient aldehydes are fully satf urated and converted into volatile products having no aiiinity for the oil or fat. The trioxide also destroys the sulphide of hydrogen whenever present.

The relative amount of sulphuric trioxide and oil varies in the case of every oil,`depend 'ing upon the quantity of substance in the oil which has to be destroyed or removed. This is a matter that can only be decided by analysis or experiment in each individual case. `I may state, however, that in purifying crude green olive oil from 0.2 to 0.4 per cent. of sulphuric trioxide gives excellent results, comipletely removing every trace of chlorophyel, yand converting the impure oil into an ideally pure substance. I have employed as little as 0.1 per cent. with equally good results.

The process is almost instantaneous, as de- .composition of the sulphuric trioxide takes In those IOO IIO

ide vapor-depends upon a variety of considerations and can only be decided by observation of the oil that is being purified. In the case e. g. of benzine, no air is required, but crude petroleum oil requires a considerable quantity; This 'quantity depends upon the facility with which the oil under treatment decomposes the trioxide. A good rough, practical rule is to use such a quantity of air that` when mixed With the trioxide vapor lche total volume equals the bulkof the oil.

Having now particularly described and ascertained the nature of my said invention and in what manner the same is to be performed,'l `declarethat what I claim is- 1. The process herein described of purifying oils and fats which consists in irstvaporizing the solid sulphuric trioxide and then injecting the gas into the oil or fat, substantially as set forth.

2. The process herein described of purifying oils and fats, which consists in first vaporizing the solid sulphur-ic trioxide, diluting the 'same with Va neutral gas and then injecting the mixture into the oil or fatfsubstantially as set forth.

Y WALTER MILLS.

Witnesses: v

- G. F. REDFERN,

JOHN E. BoUsFIELD,

Of the firm of G. F. Redfern df; Oo., 4 South Street, Fz'otsbury, London, Patent Agents. 

